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apple2gs: fix slow cycles to a more correct value. (MT#08240) [R. Belmont]

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This commit is contained in:
arbee 2022-04-12 21:25:03 -04:00
parent 58d95e7ec7
commit 53a0ae7d11
1 changed files with 3 additions and 1 deletions
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4
src/mame/drivers/apple2gs.cpp
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@ -620,11 +620,13 @@ private:
// FF6ACF is speed test routine in ROM 3
// slow_cycle() - take a 1 MHz cycle. Theory: a 2.8 MHz cycle is 14M / 5.
// 1 MHz is 14M / 14. 14/5 = 2.8 * 65536 (16.16 fixed point) = 0x2cccd.
#define slow_cycle() \
{ \
if (!machine().side_effects_disabled() && m_last_speed) \
{\
m_slow_counter += 0x0001999a; \
m_slow_counter += 0x0002cccd; \
int cycles = (m_slow_counter >> 16) & 0xffff; \
m_slow_counter &= 0xffff; \
m_maincpu->adjust_icount(-cycles); \